The arrangement of the head, neck and shoulder muscles make the task of maintaining the balancing of the head on the neck burdensome due to the highly reduced arm with respect to the fulcrum of the head suspension system. This is due to the fact that the cervical vertebrae are a structure similar to overhanging beams which has to be self-supporting, which implies that no other osteo-muscular component of the body helps to support the load of the head-neck system in vertical, lateral, oblique and sagittal direction. Thus, the working load required to maintain the head balanced in a position in which sight is horizontal is particularly burdensome. Indeed, the human body employs about twenty muscles between the right and left side of the neck to prevent the head from falling downwards. Such muscles in the side-rear area of the neck serve to contribute to generating the muscular contraction to maintain the head in horizontal position. Such muscles are obligated to develop an isometric force of 25-35 kg to maintain the head in horizontal position, otherwise the head would tend to move, typically downwards. Various cervical pathologies are detected in subjects employed in works forcing them to keep their head fixed in certain positions for an increased number of hours a day. The subjects most at risk are video terminal operators, radar operators, musicians, drivers of heavy vehicles and in particular individuals who drive military means, especially because they are also forced to wear heavy safety helmets. In particular, the damage to the cervical vertebrae of helicopter pilots depends mainly:                on the weight of the helmets, and on the related safety goggles, worn by military pilots and their crew, which make the situation worse due to the additional load applied to the head-neck system;        on the further weight of night vision goggles, which are increasingly often also used in military operations, which is combined with the fatigue of the neck musculature due to a continuous rotation of the head required by the limited angle of vision of the night vision goggles themselves;        on the increased level of vibrations, affecting also the most sophisticated and modern helicopters, which is capable of generating severe stress on the entire spine, a stress which intensifies precisely at the cervical level.        
The painful contractures and pathologies of the neck musculature are more frequent in helicopter pilots who mainly operate when there is poor lighting, because they wear heavy night vision goggles. It is known that to improve the muscular balancing system of the head, it has been experimented to reduce the force of contraction generated by the neck muscles by applying a counter-balancing weight to the occipital region, e.g. of 300-500 grams, against about 25-35 kg of effort required by the muscles to keep the head in the horizontal position. In particular, it has been found that, when a motorcycle helmet is used, about 700 grams of counter-balancing weight are needed to reduce the effort of the driver and accordingly increase the comfort conditions. Moreover, as mentioned above, when there is an additional need, for example, for night vision goggles in addition to the helmet, which in themselves are heavy and protrude with respect to the front part of the head, there is an additional stress requiring more adequate solutions, while also taking into account the fact that there is a need for the pilot and other crew members—especially in a combat helicopter—to have complete freedom of movement of at least the head-neck-upper part of the chest system. The known solutions do not succeed in adequately resolving the problem of the tendency of the head to move, in particular downwards.
Moreover, it would be advantageous to be able to adjust the balancing of the loads, in particular as a function of the position of the center of mass of the head-helmet system. A further need is to allow adjustments based on individual physical characteristics, such as the head conformation, or based on the comfort conditions specific for each pilot.